I'm on Mac system 10.5.8. When launching Illustrator and InDesign CS3 I get the error message-

FMCore has stopped. Please start it from the System Preferences pane.

I've looked in the System Preference, but can't find reference to FMCore. Can someone tell how to find it. The only reference on the forum relates to Snow Leopard, but I still need to find it in System Preferences. Help is Much appreciated.

I believe you have Suitcase Fusion installed go back the the System Preference accessed Apple Menu and at the bottom you should see something related to Suitcase. Click on it and I believe you can activate it from there.

Your tile has a mistake of calling it FNCore it is FMCore meaning Font Management Core.